Novel electrochromic compositions based on diketopyrrolopyrroles

Compositions containing (a) at least one 1,4-diketopyrrolo[3,4-c]pyrrole of the formula I, II, IIa, III or IV (I) (II) (IIa) (III) (IV) and (b) an auxiliary redox system from the ferrocyanide, ferrocene or ammonium iron(II) sulfate series in combination with at least one conductive salt (c), where, in the formula I, R and R2 are, for example, -H and R1 is -SO3Na, in the formulae II and IIa, R and R3 are, for example, -H, R1 is -SO3H and p is 3, in the formula III, R4 and R5 are, for example, phenyl and R6 and R7 are, for example, methyl, and in the formula IV R8 and R9 are, for example, phenyl, are suitable as electrochromic materials in display systems. Compositions containing (a) at least one 1,4-diketopyrrolo(3,4-c)pyrrole of the formula I, II, IIa, III or IV (* CHEMICAL STRUCTURE *) (I) (* CHEMICAL STRUCTURE *) (II) (* CHEMICAL STRUCTURE *) (IIa) (* CHEMICAL STRUCTURE *) (III) (* CHEMICAL STRUCTURE *) (IV) and (b) an auxiliary redox system from the ferrocyanide, ferrocene or ammonium iron(II) sulfate series in combination with at least one conductive salt (c), where, in the formula I, R and R2 are, for example, -H and R1 is -SO3Na, in the formulae II and IIa, R and R3 are, for example, -H, R1 is -SO3H and p is 3, in the formula III, R4 and R5 are, for example, phenyl and R6 and R7 are, for example, methyl, and in the formula IV R8 and R9 are, for example, phenyl, are suitable as electrochromic materials in display systems.